Winter Haven, Florida-- By sunset, Luis Pena was carrying plywood in the front door of his Winter Haven home to fix damage caused by a home invasion.

At 6:00 a.m. Monday, Pena was awakened by the sound of someone trying to get in the back of the house. Police say it was 40-year-old Mitchell Large. Pena, his wife and his 27-year-old son each armed themselves with guns, and fired a warning shot to scare Large off.

According to police, when Large was undeterred and entered the kitchen, the Pena family aimed and fired.

Michelle Brooks was Large's girlfriend. They lived together not far away. She spoke exclusively to 10 News.

"I tried to make him stay home," said Brooks. "If he had, he would still be alive. Now, I'll never get to say goodbye."

Brooks explained Large had been diagnosed years ago as a manic-depressive, and may have been confused Monday morning, entering what he thought was his residence.

"He wasnt in his right mind. Why would he keep going in if he heard a warning shot? It just doesnt make any sense," said Brooks.

Large was a foreman at a concrete construction company. His employees were stunned by the news..

"I couldnt believe what I heard. He didnt seem like the type of person to do any of that," said one of his employees. "He was a normal, good guy. He worked hard to provide for his three children. I respected that."